A beam of electromagnetic energy, such as a beam of X-rays, is passed through objects, such as manufactured parts used in gas turbine engines. An ionization detector is responsive to the electromagnetic energy passing through the object to inspect it for flaws and departures from specifications. The ionization detector has one or more dielectric substrates having closely spaced conductive detector traces carrying small signals produced in response to ionization of a gaseous dielectric by the electromagnetic energy passing through the inspected object. Those signals are on the order of pico-amperes and micro-volts. Electrical crosstalk and charge leakage distort small signals carried by closely spaced conductive traces, especially in a charge-based system such as an ionization detector. Contamination and humidity also distort those signals. Inspection systems can thus produce distorted images of the inspected parts. Therefore, a need exists for a means to minimize such distortion in an ionization detector used in an object inspection apparatus.